Photoelectrochemical Approach to Solar Fuels
NREL researchers strive to ultimately understand and control the intricate interplay of photoelectrochemical and photo- and electrocatalytic reactions in solar fuels.
This includes understanding the dynamics and energetics of charges, the subsequent transfer to a catalytic site and the control by tuning the crystal phase, morphology, surface structure, defects, and surface chemistry.
Plasmonic Hot-Hole Transfer in Gold Nanoparticle-Decorated Transition Metal Dichalcogenide Nanosheets
Transient absorbance measurements showed that molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2) decorated with gold nanoparticles show hot-hole transfer from the gold to the transition metal dichalcogenide, producing a charge-separated state.
- Gold nanoparticle-decorated mono- to few-layer transition-metal dichalcogenides nanosheets were prepared using liquid-phase exfoliation and direct growth of gold nanoparticles from solution.
- Thin films were deposited by blade coating.
- Photogenerated carrier dynamics in these nanosheets were studied using transient absorbance.
Significance and Impact
Efficient injection of hot holes at the metal-semiconductor interface represents an important advance in harnessing plasmonic dissipation pathways to generate long-lived carriers suited for solar-driven light harvesting and catalysis.
Scanning Eletrochemical Microscopy Reveals Hydrogen Evolution Reaction and Semiconducting Properties of MXene
Basal Plane Hydrogen Evolution Activity from Mixed Metal Nitride MXenes Measured by Scanning Electrochemical Microscopy, Advanced Functional Materials (2020)
2D mixed-metal nitride MXenes M-Ti4N3Tx (M = V, Cr, Mo, Mn) were synthesized by a novel solution-based method and characterized via scanning electrochemical microscopy.
Hydrogen evolution reaction activity results from the transition metal ions comprising the outer layer of the basal plane in MXenes, which is distinct from other 2D materials such as transition metal dichalcogenides where the catalytically active transition metals are only exposed on the edges.
There is much debate in the community surrounding whether MXenes are intrinsically metals or can exhibit semiconducting properties, and this report conclusively demonstrates the latter.
Significance and Impact
Scanning electrochemical microscopy data showed the first experimental evidence that MXenes exhibit hydrogen evolution reactionactivity from their basal planes, the large area "flat" part of the 2D structure. Additionally, scanning electrochemical microscopy provided evidence for semiconducting behavior, which represents only a handful of reports showing that MXenes can be semiconducting in addition to metallic.
Senior Scientist and Group ManagerNathan.Neale@nrel.gov